Exemplary embodiments of the present invention relate to a seat belt for a vehicle, comprising a belt webbing that comprises several belt webbing layers and, in a shoulder belt region and a lap belt region, at least one belt interior located between at least two belt webbing layers and to which a gas can be applied, wherein the belt webbing is guided through an opening of a latch plate that can be inserted into a buckle, by means of which latch plate the belt webbing is, if the seat belt is fastened, deflected at a lower deflection point in a transitional region from the lap belt region to the shoulder belt region, and wherein a gas passage connecting at least two sections of the belt interior is provided at the lower deflection point between the at least two belt webbing layers.
German Patent Document DE 91 03 845 U1 discloses a restraint device for occupants. The restraint device comprises a seat belt with a buckle and a deflection fitting. The seat belt is designed as a flat tube and coupled to a device by means of which the tube, in an accident-related sudden deceleration of the vehicle equipped therewith, can be inflated within fractions of a second with a gas, turning it into a tube with a substantially circular cross-section.
German Patent Document DE 198 57 517 A1 discloses an inflatable belt webbing for a seat belt made of a two-layered woven fabric. A webbing width of the fabric is divided into three parts of approximately equal width, these being a left-hand outer part, a central part and a right-hand outer part, the warp threads of the parts differing in thickness. The outer parts and the inner part are folded in such a way that they form a flattened Z. In two folding zones, at least one tear-open thread is woven or sewn into the fabric, the tear-open thread breaking under a presettable breaking load, so that the individual fabric layers move in preset directions and the belt webbing is opened by means of a blown-in explosion gas to form an inflated belt bag. A gas delivery hose is provided to apply gas to the belt webbing, the gas delivery device is placed in the belt webbing between darts. For inflation, the belt webbing is supplied with the explosion gas by means of the gas delivery hose.
European Patent Document EP 1 053 133 B1 describes a three-point belt with shoulder and lap belt parts of a belt webbing, which are inflatable at least in the shoulder belt region. At a deflection point, the seat belt is provided with an insertion part that can be inserted into a buckle, the belt webbing being deflected in a transitional region from the lap belt part to the shoulder belt part at the deflection point if the seat belt is fastened. In the region of the insertion part, the belt webbing is provided at the deflection point with a gas passage for establishing a gas flow connection between the belt interiors of the shoulder belt part and the lap belt part. An opening cross-section of the gas passage is smaller than the cross-section of a filled belt interior, which can be filled continuously and extends in the belt webbing that forms the shoulder and lap belt parts as well as in the transitional region. At least in the belt interior of the transitional region guided around the deflection point, the gas passage forms a radially reinforced gas line via the opening cross-section of which the interiors of the shoulder belt part and the lap belt part can be inflated. The gas passage consists of a tubular piece having a relatively high rigidity in the radial direction, so that the opening cross-section formed by the gas passage does not collapse as the belt webbing is deflected about the deflection point. The seat belt further comprises a gas feed in the region of an end of the lap belt part which is opposite the transitional region.
Exemplary embodiments of the present invention are directed to providing an improved seat belt for a vehicle.
The seat belt for a vehicle comprises a belt webbing having several belt webbing layers and, in a shoulder belt region and a lap belt region, at least one belt interior that is located between at least two belt webbing layers and to which a gas can be applied, wherein the belt webbing is guided through a recess of a latch plate that can be inserted into a buckle, by means of which latch plate the belt webbing is, if the seat belt is fastened, deflected at a lower deflection point in a transitional region from the lap belt region to the shoulder belt region, and wherein a gas passage connecting at least two sections of the belt interior is provided at the lower deflection point between the at least two belt webbing layers.
The two sections of the belt interior are formed by the deflection of the belt webbing in the region of the latch plate and the resulting tensile and compressive forces.
According to the invention, the gas passage is represented by a tube which is flexible, i.e., collapsible, at least in the radial direction.
If gas is applied to the belt interiors in order to increase a surface area of the belt webbing, which happens if the vehicle collides with an obstacle, the tube forms an open flow cross-section due to the internal pressure acting in the interior of the tube. In this way, even the shoulder region of the seat belt can be filled with gas from a gas generator located at a lower mounting point of the belt webbing, even though the belt webbing is deflected at the lower deflection point. This results in an optimized gas filling of the belt webbing. The gas may be, for example, air or reaction gases generated in a pyrotechnic gas generator and by the ignition of the fuel charge.
In a particularly preferred further development of the invention, the tube is compressed flat between the belt webbing layers if no gas is applied to the belt webbing. Due to the fact that the gas passage is a collapsible tube lying flat between the belt webbing layers, the belt webbing is flexible and can be paid out and retracted with little effort. The belt webbing can further be easily moved within the latch plate. Due to the flexible design of the tube and therefore of the belt webbing, the belt webbing can further be optimally positioned on the vehicle occupant, so that a maximum protection of the vehicle occupant is always ensured. In addition to advantageous haptics, the flexibility of the belt webbing and the simple pay-out and retraction thereof result in great comfort for the vehicle occupant.
The tube is further preferably designed to be seamless, improving its tightness against radially escaping gas. According to a further development of the invention, the tube is woven seamlessly using generally known methods. The fabric is preferably a synthetic fiber fabric, in particular a polyester yarn fabric, which offers a particularly high stability. As the tube is made of a woven fabric, it can be introduced into the belt webbing in a flat form in a particularly simple way.
An inside of the tube is then preferably coated with a fluid-impermeable layer, in particular latex of silicone. This makes the tube fluid-tight. As a result, the connection of the belt interior between the lap belt region and the shoulder belt region is not broken in the filling process, because a gas escape from the tube in the radial direction is avoided.
In order to avoid a slippage of the tube within the belt webbing while the seat belt is fastened and unfastened and in the fastened state thereof, the tube is secured to at least one of the belt webbing layers according to a further development of the invention. This may be carried out by bonding the tube to the inside of the respective belt webbing layer. The resulting adhesive seam preferably has a small width dimension, allowing an optimized unfolding of the tube.
If the latch plate is inserted into the buckle and the belt webbing is paid out to its minimum extent, the tube preferably extends no further than an upper deflection point. This means that the tube always extends maximally to the upper deflection point if the seat belt is fastened, this deflection point being preferably located in the upper region next to the vehicle occupant or the vehicle seat. In addition, the inflatable belt interior in the shoulder belt region likewise extends no further than the upper deflection point at minimum pay-out length. In this way, an inflation of the belt webbing behind the upper deflection point is avoided. This in turn minimizes the gas quantity required to fill the belt interiors. In addition, any deformation of, damage to or loosening of paneling within the vehicle, behind which the belt webbing runs, is avoided, so that the risk of injury to the vehicle occupant(s) is minimized.
In a particularly preferred further development of the invention, the tube is directly coupled to the gas generator, thereby forming a so-called gas lance. This advantageously results in a further improvement of the unfolding of the tube and the belt webbing, in particular in a shortening of the time leading to the unfolding.
The width of the belt webbing is preferably divided into several parts of approximately equal width, the belt webbing being folded once or several times parallel to its longitudinal dimension. In the region of the interior folded layers, the belt webbing is preferably woven thinner than in the region of the two outer folded layers. As a result, the belt webbing has an advantageously minimal thickness, a high flexibility and a low weight.
The folded layers are joined to one another by tear-open threads that break as the gas is applied to the belt webbing, followed by the unfolding of the belt webbing. During a collision of the vehicle, a surface area of the belt webbing is therefore increased as a result of its unfolding, thereby minimizing the load acting on the vehicle occupant.
The tear-open threads are inserted at the edges into the folded layers of the belt webbing in such a way that they form seams extending in the longitudinal direction of the belt webbing, these seams breaking when the gas acts on the belt interiors, i.e., when a resulting predetermined tensile load is exceeded. By the tear-open threads, the individual folded layers of the belt webbing are securely joined at the edges. The tear-open threads are inserted into the belt webbing in such a way that the latter maintains its flat shape in use. Furthermore, a defined unfolding of the belt webbing under the action of the gas is obtainable. In combination with the gas-tight design of the gas passage, an internal pressure within the gas passage can be maintained for a longer time, thereby facilitating an optimized and complete unfolding of the belt webbing.
In a particularly preferred variant, the width of the belt webbing is divided into three parts of approximately equal width, the belt webbing being folded twice parallel to its longitudinal dimension in such a way that it has a flattened Z-shape. After the unfolding of the belt webbing, a contact surface of the belt webbing on the vehicle occupant becomes almost three times as large as in the folded state, so that the force acting on the vehicle occupant is reduced in the region of the unfolding of the belt webbing.
Corresponding parts are identified by the same reference numbers in all figures.